Identifying a state of a data storage drive using an artificial neural network generated model

ABSTRACT

The state or condition of a data storage drive, or a subsystem within a drive, may be evaluated by comparing a set of selected parameter values, converted into a trial vector, with a number of model or exemplar vectors, each of which was represents a particular state or condition of a sample drive. Examples of such conditions may include “good”, “marginal”, “unacceptable”, “worn”, “defective”, or other general or specific conditions. Sets of parameter values from the drive are converted into input vectors. Unprocessed vectors are then processed against the input vectors in an artificial neural network to generate the exemplar vectors. The exemplar vectors are stored in a memory of an operational drive. During operation of the drive, the trial vector is compared with the exemplar vectors. The exemplar vector which is closest to the trial vector represents a state which most closely represents the current state of the drive. Thus, a high similarity between the trial vector and an exemplar vector which represent a “good” drive is likely to have come from a “good” drive.

RELATED APPLICATION DATA

The present invention is related to commonly assigned and co-pendingU.S. application Ser. No. 10/______ [TUC920040095US1], entitledIDENTIFYING A STATE OF A SYSTEM USING AN ARTIFICIAL NEURAL NETWORKGENERATED MODEL, filed on the filing date hereof, which application isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to system diagnostics and, inparticular, using an artificial neural network to generate a modelrepresenting one or more possible states of a data storage drive andcomparing an actual state of the drive to the model.

BACKGROUND ART

Numerous types of systems include automated processes to generate one ormore parameters which may be used to evaluate the current state of thesystem. The automated process may also be used to improve systemperformance or even repair certain defects or faults. For example, adata storage drive, such as a tape drive, may include an adaptiveequalizer with many finite impulse response (FIR) taps whose inputcoefficients are automatically modified to optimize system performance.

However, it may be difficult to assess the quality of the result of anautomated process because of obscure relationships between the measuredparameters and the system response. It will be appreciated that if theintegrity of the parameter values is not verified, there is a risk thatthe automated process produces an undesirable system response. Thus, notonly might the process fail to improve performance but, if the parametervalues are undetectably invalid, may also cause the system to failcompletely.

For example, in an adaptive equalizer of a tape drive, FIR tap valuesare computed from information captured from the storage drive. If theinformation is corrupted, or if execution of the algorithm which is usedto compute the tap values is corrupted, the FIR tap values will beinvalid. More specifically, a media defect or servo error may corruptthe captured information. Similarly, an overflow or underflow may occurduring the execution of the FIR tap algorithm, resulting in tap valueswhich bear no relation to the proper results. Or, rather than thecaptured information being invalid, the information may result in thecreation of tap values which are outside the range of values which canbe handled by the equalizer. In each of these circumstances, the invalidor improper condition of the tap values may be undetected.

Consequently, there remains a need for an automated process whichprovides an assessment of the quality of parameter values which are usedto adjust the system.

SUMMARY OF THE INVENTION

The present invention provides an assessment the state or condition of adata storage drive or a system within a drive, such as an adaptiveequalizer. Examples of such conditions may include “good”, “marginal”,“unacceptable”, “worn”, “defective”, or other general or specificconditions, depending on the specific system being evaluated and thedesired specificity of the evaluation.

Sets of n parameter values each from a model drive or system, such asFIR tap values of an equalizer, are converted into n-tuple inputvectors. Unprocessed n-tuple vectors are then processed against theinput vectors in an artificial neural network (“ANN”) to generate a setof n-tuple exemplar vectors. The ANN preferably includes three stages, aglobal conditioning stage, a vector separation stage and a vectorconsolidation stage, to fine tune the creation of the exemplar vectors.Each exemplar vector will thereby represent a particular potential stateor condition of the drive or system. The exemplar vectors are stored ina memory of an operational drive to be evaluated.

During operation of the drive, a set of n selected parameter values areconverted into an n-tuple trial vector. The trial vector is comparedwith the exemplar vectors. The exemplar vector which is closest,measured by the distance between the two, to the trial vector representsa state which most closely represents the current or actual state of thedrive or system. Thus, a high similarity between the trial vector and anexemplar vector which represent a “good” drive is likely to have comefrom a “good” drive. Conversely, a high similarity between the trialvector and an exemplar vector which represent an “unacceptable” drive islikely to have come from a “unacceptable” drive.

Optionally, the presence of predetermined states may be flagged orlogged for follow-up attention. Additionally, if the distance betweenthe trial vector and the closest exemplar vector is greater than apredetermined distance, the current state of the drive or system may bea previously unknown state and the trial vector may subsequently beanalyzed and used as another exemplar vector. Alternatively, such asituation may indicate that the parameters underlying the trial vectorare invalid, thereby triggering a flag for immediate attention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a summary block diagram of an embodiment of the presentinvention to generate exemplar vectors and evaluate trial vectors;

FIG. 2 is a block diagram of an embodiment of the present invention togenerate exemplar vectors;

FIG. 3 is a plot of a 3-tuple exemplar vector;

FIG. 4 is a flow chart of the global conditioning stage in the processof generating exemplar vectors;

FIG. 5 is a vector map of input vectors and unprocessed exemplar vectorsduring the global conditioning stage of exemplar vector creation;

FIG. 6 is a representation of the application of the input vectors tothe exemplar vectors;

FIG. 7 is a flow chart of the vector separation stage in the process ofgenerating exemplar vectors;

FIG. 8 is a vector map of input vectors and conditioned exemplar vectorsduring the vector separation stage of exemplar vector creation;

FIG. 9 is a flow chart of the vector consolidation stage in the processof generating exemplar vectors;

FIG. 10 is a vector map of input vectors and separated exemplar vectorsduring the vector consolidation stage of exemplar vector creation;

FIG. 11 is a vector map of input vectors and consolidated exemplarvectors following the vector consolidation stage of exemplar vectorcreation;

FIG. 12 is a block diagram of a system to be evaluated in accordancewith the present invention;

FIG. 13 is a vector map of a trial vector and exemplar vectors; and

FIG. 14 is a block diagram of a data storage drive having FIR tap valuesto be evaluated in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Overview

FIG. 1 is a block diagram of an embodiment 100 of the present inventionwhich may be implemented in a system to evaluate performance parameters.The embodiment 100 includes two sections 110 and 130. In the firstsection 110, exemplar vectors, which represent potential states orconditions of a system to be evaluated, are generated from exemplaryparameter sets. In the second section 130, implemented in the systemitself, a trial vector is generated from actual parameters collectedfrom the system during its normal operation and compared to the exemplarvectors. The exemplar vector which most closely matches the trial vectorprovides a representation of the current state of the system.

The first section 110 receives one or more sets 112 of parameters in amodule 114, each set 112 representing a potential state of the system.Such states may be as general as “good”, “marginal”, “unacceptable” and“defective”. Alternatively, the states may be as specific as “worn”,“low tape tension”, “excess media speed”, etc. The module 114 convertsthe parameter sets 112 into vectors 116 which are input into anartificial neural network (“ANN”) 118. Also input into the ANN 118 areone or more unprocessed vectors 120. the ANN 118 processes theunprocessed vectors 120 and outputs a like number of exemplar vectors122.

The second section 130, implemented in the system to be evaluated,receives one or more parameters 132 in a module 134 while the system isin operation, the parameters 132 representing the current state of thesystem. The module 134 converts the parameters 132 into a trial vector136 which is input into a calculator 138 along with the exemplar vectors122. The calculator 138 determines which exemplar vector has the leastdistance to the trial vector and how close the trial vector 136 is tothat “closest” exemplar vector 122. This minimum distance 140 may becompared in a comparator 142 to a predetermined value. If the minimumdistance 140 is less than the value, the parameters 132 from which thetrial vector was created may be deemed to be valid and the closestexemplar vector 122 may be deemed to be a reasonable representative ofthe current state of the system. Thus, the general condition of thesystem may be determined to be “good”, “marginal”, “unacceptable” or“defective” or certain problems may be specifically identified. Bycontrast, if the minimum distance 140 is greater than the value, theparameters 132 from which the trial vector was created may be deemed tobe invalid (or represent a condition not yet experienced in the system).In either event, an appropriate indicator 144 may be generated andlogged or flagged for maintenance or a warning.

Exemplar Vector Creation

FIG. 2 illustrates a block diagram of an apparatus 200 of the presentinvention which may be implemented to generate exemplar vectors. Afterdeciding which parameter or parameters are to be evaluated, sets of theparameters are obtained, each set having parameter values which, incombination (if more than one parameter is used), represent a particularstate or condition of the system. Referring again to the example of anadaptive equalizer for a data storage drive, the FIR filter may have 17taps. If the equalizer is the “system” to be evaluated, the 17 tapcoefficients may be used as the parameters. A test storage drive may beput into operation and, when the equalizer is functioning properly, the17 coefficient values may be recorded and stored, such as in a database202, as one set of parameters which represent a “good” state. Becauseother combinations of tap coefficients may occur when the equalizer isoperating properly, such other sets of coefficient values may berecorded and stored to represent a “good” state. Similarly, the testdrive may intentionally be set to operate in a marginal manner and theresulting tap coefficients recorded and stored to represent a “marginal”state. As with the “good” states, there may be different circumstanceswhich result in a “marginal” state and the various other sets ofcoefficients may be recorded and stored. In a like manner, sets ofparameter values may be recorded and stored to represent “unacceptable”states as well as other general and specific states of interest. It willbe appreciated that references in this description to a data storagedrive, an equalizer and FIR tap values are merely illustrative and arenot meant to be limiting. The present invention may be implemented withnumerous systems which have measurable parameters. It should also benoted that it is not necessary that the parameters have a physicalrelationship or dependency to each other.

Depending upon the particular system to be evaluated, not all of theavailable parameters may be necessary to obtain a satisfactoryevaluation. For example, of the 17 tap coefficients in the exemplaryequalizer, only three or four may be sufficient to represent the systemstates of interest. Consequently, the three or four (or some othernumber) of the most significant parameters may be selected 204 forfurther processing resulting in a more manageable sparse representationof the system parameters. Computations and analysis are simplified withonly an insignificant reduction in accuracy. The selected parameters arepreferably those which have the greatest effect on system response. Insuch a manner, q parameter values in each of M parameter sets which havebeen recorded and stored in the database 202 may be reduced to nparameter values in the optional parameter selection 204 module.

In some systems, there may be some ambiguity associated with theparameters, thereby obscuring the relationship between the parametervalues and the physical “world” which is to be affected. For example, itmay be difficult to determine what is happening within the equalizermerely by looking at FIR tap coefficient values because the tap valuesare a time domain representation of the frequency domain result. Thus,it may be desirable to convert the values from the time domain to themore recognizable state of the frequency domain, such as by using aDiscrete Fourier Transform. Such a conversion, or other comparableoperation, may be accomplished in an optional pre-processor 206. Thepre-processor 206 may also be used when the raw parameter values aresamples in time, each of which provides little indication of the systemoperation. Thus, pre-processing may generate a significantly moremeaningful representation of the system state. It will be appreciatedthat the pre-processor 206 may be configured to perform variousoperations, depending upon the system, the form of the parameters andthe desired form of the output. Thus, the Discrete Fourier Transformnoted above is merely an example of one such operation and is not meantto be limiting.

The M sets of n parameter values are then processed by a vector creator208 to generate M n-tuple vectors. FIG. 3 illustrates an example of avector 300 in which n=3. Each of the three vector elements is plottedalong a corresponding unit vector in n-dimensional space and theresulting vector 300 has both a magnitude and a direction in suchn-space.

In a further optional operation, the magnitudes of the vectors may benormalized to a common scaled magnitude (such as 1) in another unit 210of the apparatus 200 of the present invention. Normalization removesamplitude (size) variations among the vectors while preserving theirintrinsic shapes, thereby facilitating the comparison and matching ofvectors in subsequent operations. As a result, the vectors will differonly in their direction and vector-to-vector variability is reducedwithout compromising the shape described by the components of thevector. The normalized vectors, or the vectors created in the vectorcreator 208 if normalization is not performed, are the M n-tuple inputvectors for the next stage, an artificial neural network 230.

In addition to the input vectors whose creation has just been described,unprocessed exemplar vectors are also created for input to the ANN 230for processing. J n-tuple unprocessed vectors are created in a secondvector creator 212 with random initial weights provided by a randomizer214 or other comparable component. The unprocessed vectors may benormalized in a normalizer 216 to the same common magnitude as the inputvectors. The vector creators 208 and 212 need not be separate componentsbut may comprise a single component. Similarly, the normalizers 210 and216 need not be separate components but may be a single component.

Both the input vectors and the unprocessed exemplar vectors are input tothe ANN 230. The ANN 230 provides an unsupervised learning process, suchas that which is used to calculate a Kohonen self-organizing feature map(“SOFM”). In general, a number of weight matrix vectors are randomlyinitialized and an output node is associated with each weight matrixvector. Input vectors are repeatedly presented to the weight matrixvectors. The difference between the weight vectors and the input vectorsis fed back to the network and the weights are progressively adjusted.After a predetermined number of iterations (epochs), each input vectorbecomes associated with an output node, without actually havingspecified the output node. The details of SOFMs and related processesare well known and need not be described further herein.

In a first stage, global conditioning 232, of the ANN 230, theunprocessed exemplar vectors are arrayed in a field which also containsthe input vectors. However, because of their random initial weights,some or all of the unprocessed exemplar vectors may be remote from anyinput vector and therefore outside a range of probable values (suchrange being roughly defined by the M input vectors). The first stage232, therefore, rearranges the unprocessed exemplar vectors within therange of probable values. Referring to the flow chart of FIG. 4,beginning with the initial configuration of J unprocessed exemplarvectors (step 400; see also FIG. 5), an epoch counter is initialized(step 402) to the number of epochs over which each unprocessed exemplarvector is to be processed during global conditioning. A vector counteris similarly initialized (step 404) to the number of input vectors usedin the process. it will be appreciated that any of the various countersused in the various routines of the present invention may insteadcount-up to be subsequently incremented. An input vector (such as I₀) isthen selected (step 406), an exemplar vector counter is initialized(step 408) to the number of exemplar vectors to be processed, and anexemplar is selected to be processed (step 410). The selected inputvector is then applied to the selected unprocessed exemplar vector (step412) and the selected unprocessed exemplar vector is updated. Each ofthe n components of the selected unprocessed exemplar vector is adjustedby a fraction a, of the difference between the selected input vector andthe selected unprocessed exemplar vector (step 414), thereby shiftingthe location of the selected unprocessed exemplar vector closer to theselected input vector (as indicated by the arrows in FIG. 5). Forexample, if n_(i) and m_(i) represent a vector component of an exemplarvector and an input vector, respectively, the adjustment to n_(i) willbe n_(updated)=n_(i)+α(m_(i)−n_(i)).

This adjusting step 414 will be referred to as vector “updating” in thedescriptions below of the vector separation 234 and vector consolidation236. If the exemplar counter is not yet zero (step 416), the exemplarcounter is decremented (step 418) and the process repeats by applyingthe same selected input vector to a newly selected exemplar vector(steps 410-416). If the exemplar counter has reached zero, adetermination is made whether the selected input vector has been appliedto all of the exemplar vectors (step 420). If not, the input vector isdecremented (step 422), a new input vector is selected (step 406) andthe process repeats (steps 408-422) until all of the input vectors havebeen applied to all of the exemplar vectors during the current epoch (asillustrated generically in FIG. 6). Then, a determination is madewhether the vectors are to be processed through further epochs (step424). If so, the epoch counter is decremented (step 426) and the processrepeats (steps 404-424) until the epoch counter reaches zero, at whichtime global conditioning is complete (step 428). It should be noted thatthe order of some of the above described steps may be reversed orchanged, with appropriate modifications to later steps in the process.It should also be noted that the fraction α₁ need not be a constant butmay be adjusted as the global conditioning progresses, therebyautomatically fine tuning the process.

In a second stage, vector separation 234, of the ANN 230, theconditioned exemplar vectors undergo further processing. Referring tothe flow chart of FIG. 7, beginning with the ending configuration ofconditioned exemplar vectors (step 700; see also FIG. 8), an epochcounter is initialized (step 702) to the number of epochs over whicheach unprocessed exemplar vector is to be processed during vectorseparation. A vector counter is similarly initialized (step 704) to thenumber of input vectors used in the process. An input vector (such asI₀) is selected (step 706). Next, the distance from the selected inputvector to each exemplar vector is calculated (step 708). The distancemay be calculated as the Euclidean distance, such as by finding thesquare root of the sum of the squares of the difference of each of the ncomponents of the two vectors. The exemplar vector which is the closestto the selected input vector is selected (step 710) as are the twoexemplar vectors which adjoin the selected exemplar vector (step 712).In FIG. 8, exemplar vector E_(J) is closest to the selected input vectorI₀; the two adjoining vectors are E₀ and E₂. These three exemplarvectors are updated (step 714) using an adjustment factor α₂ which maybe the same or different from the adjustment factor α₁ used duringglobal conditioning. The adjustment factor may itself also be adjustedas the epochs continue. If the vector counter has not yet reached zero(step 716), the counter is decremented (step 718) and the process isrepeated with a new input vector (steps 706-718). If the vector counterhas reached zero, a determination is made whether the process is to beperformed through further epochs (step 720). If so, the epoch counter isdecremented (step 722) and the process repeats (steps 704-720) until theepoch counter reaches zero, at which time the vector separation ends(step 724).

In a third, vector consolidation 236, of the ANN 230, the separatedexemplar vectors undergo still further processing. Referring to the flowchart of FIG. 9, beginning with the ending configuration of separatedexemplar vectors (step 900; see also FIG. 10), an epoch counter isinitialized (step 902) to the number of epochs over which separatedexemplar vectors are to be processed during vector consolidation. Avector counter is similarly initialized (step 904) to the number ofinput vectors used in the process. An input vector (such as I₀) is thenselected (step 906) and the distance from the selected input vector toeach exemplar vector is calculated (step 908). As before, the distancemay be calculated as the Euclidean distance between the selected inputvector and an exemplar vector. The exemplar vector which is the closestto the selected input vector is selected (step 910); in FIG. 10,exemplar vector E_(J) is closest to the selected input vector I₀. Theclosest exemplar vector is updated (step 912) using an adjustment factorα₃ which may be the same or different from the adjustment factors α₁ andα₂ used during global conditioning and vector separation. Similarly, theadjustment factor may itself be adjusted as the epochs continue. If thevector counter has not yet reached zero (step 914), the counter isdecremented (step 916) and the process is repeated with a differentinput vector (steps 906-916). If the vector counter has reached zero, adetermination is made whether the process is to be performed throughfurther epochs (step 918). If so, the epoch counter is decremented (step920) and the process repeats (steps 904-920) until the epoch counterreaches zero, at which time vector consolidation ends (step 922) with afinal alignment of the J exemplar vectors with the M input vectors, asillustrated in FIG. 11. In this final alignment, each exemplar vectorwill have moved to the approximate mean squared center of a group ofinput vectors, thereby associating each exemplar vector with a group ofinput vectors which represent a state or condition of the system to beevaluated. Thus, each exemplar vector is an approximate model for oneparticular system state.

The finalized exemplar vectors processed through the ANN 230 are thenrecorded or stored, such as in a database 240.

System Evaluation

FIG. 12 is a block diagram of a system 1200 to be evaluated and providesan overview of the evaluation process. State models 1212, in the form ofthe exemplar vectors previously obtained, are stored in a memory 1210 ofthe system 1200. One or more limit values 1214 are also stored in thememory 1210. Parameter values obtained from the system during itsoperation are processed by a processor 1220 to generate an n-tuple trialvector. The processor 1220 may include a module 1222 to select which ofthe operational parameters are actually included as components in thetrial vector. For example, of 17 FIR taps in the exemplary storagedrive, three or four of the most significant may be selected for furtherprocessing. And, as in the case of exemplar vector creation describedabove, pre-processing 1224 may be performed to remove ambiguities. Theselected parameters are then used to create a trial vector 1226 which ispreferably normalized 1228 to the same magnitude to which the exemplarvectors are normalized.

The trial vector and the exemplar vectors 1212 are input to a distancecalculator 1230 which calculates the distance between the trial vectorand each exemplar vector and determines which exemplar is the leastdistance to the trial vector. In FIG. 13, the exemplar vector E₁ isclosest to the trial vector Vt. The minimum distance (that is, thedistance between the trial vector and the closest exemplar vector, alsoknown as the “activation value”) is output and compared in a comparator1240 with a first predetermined limit value 1214. If the minimumdistance is less than the limit value, the operational parameters may beconsidered valid and representative of the current state of the system1200. The minimum distance indicates the degree of similarity betweenthe trial vector and the closes exemplar vector. A high degree ofsimilarity to an exemplar vector which represents a “good” systemindicates that the current state of the system is most likely also“good”. Conversely, a high degree of similarity to an exemplar vectorwhich represents an “unacceptable” system indicates that the currentstate of the system is most likely also “unacceptable”. Moreover, if theminimum distance is greater than the predetermined limit, theoperational parameters may be considered invalid. The evaluation resultmay be rejected and the system directed to repeat the evaluation, postan error or log the event for later referral by a technician.Additionally, if the minimum distance is greater than the predeterminedlimit but the operational parameters are, in fact, determined to bevalid, the trial vector may itself be recorded and included with theexemplar vectors as a model representing a previously unrepresentedstate of the system 1200.

Even more specific evaluation may also be performed. For example, if theminimum distance or activation value is less than a second predeterminedlimit (which is less than the first limit), the activation value may belogged. If the minimum activation value is greater than the secondpredetermined limit, a system calibration or other comparable operationmay be initiated. And, if the activation value is greater than a thirdpredetermined limit (which is greater than the second limit), an alarmmay be activated.

EXAMPLE

FIG. 14 is a block diagram of a data storage drive 1400, such as amagnetic tape drive, optical disc drive, magnetic disk drive or thelike. A transducer 1402 detects transitions representing stored data andrecorded on a media, such as magnetic tape, an optical disc or amagnetic disk, and converts the transitions into an analog signal.Typically, a pre-amp 1404 boosts the amplitude of the signal which isthen processed by a variable gain amplifier 1406 under the control of aprocessor or controller 1418. A sampler, such as an analog-to-digitalconverter 1410 converts the analog signal into a digital signal. Asignal processor, such as an adaptive equalizer 1420, may be used toshape the signal before a detector 1412, such as a sampled amplitudesequence detector, detects likely transition sequences. The detector1412 sends the sequences to a decoder which reproduces the original dataand transmits it to a host device.

As is known, the equalizer 1420 operates by applying a number n ofcoefficients C₀-C_(n-1) to the input signal delayed by delay registers1422 ₀-1422 _(n-1) through multipliers 1422 ₀-1422 _(n-1). The resultingn signals are summed in a summer 1426 before being transmitted to thedetector 1412. Through a feedback process, the controller 1418adaptively adjusts the coefficients to optimize the signal. In order toevaluate the performance of the equalizer 1400, the coefficient values(operational parameters) may be sent to the processor 1220 (FIG. 12) andconverted into a trial vector in the manner described above.

The controller 1408, or other comparable component, includes or accessesa memory 1416 in which are stored the exemplar vectors created asdescribed above and which represent models of various possible states ofthe drive 1400. In operation, programmed instructions direct theprocessor or controller 1418 to calculate the distance between the trialvector and each stored exemplar vector. The exemplar vector which is theclosest to the trial vector most closely represents the current state orcondition of the drive 1400.

The objects of the invention have been fully realized through theembodiments disclosed herein. Those skilled in the art will appreciatethat the various aspects of the invention may be achieved throughdifferent embodiments without departing from the essential function ofthe invention. The particular embodiments are illustrative and not meantto limit the scope of the invention as set forth in the followingclaims.

1. A data storage drive comprising: a transducer adapted to readcustomer data from a storage media; a sampler adapted to convert analogsignals read from the storage media into a digital format; a detectoradapted to identify transitions in the digital signal and a decoderadapted to generating an output substantially corresponding to thecustomer data; a memory operable to store a plurality J of n-tupleexemplar vectors representative of potential states of a system; thememory further operable to store a first predetermined value; aninterface coupled to receive a plurality n of current parameter valuesfrom the system; means for generating an n-tuple trial vector from the nparameter values; a processor operable to determine a distance betweenthe trial vector and each exemplar vector; the processor furtheroperable to identify an exemplar vector K which is the least distance tothe trial vector, the least distance comprising an activation value; anda comparator operable to compare the activation value with the firstpredetermined value, whereby if the activation value is less than thefirst predetermined value, the current state of the system ischaracterized by the exemplar vector K.
 2. The storage drive of claim 1,the means for generating the trial vector further operable to normalizethe trial vector to a predetermined magnitude.
 3. The storage drive ofclaim 1, wherein the processor is further operable to calculate theEuclidean distance between each exemplar vector and the trial vector. 4.The storage drive of claim 1, whereby, if the activation value isgreater than the first predetermined value, the trial vector is invalid.5. The storage drive of claim 1, wherein the comparator is furtheroperable to: compare the activation value with a second predeterminedvalue, the second predetermined value being less than the firstpredetermined value, and if the activation value is less than the secondpredetermined value, log the activation value and if the activationvalue is greater than the second predetermined value, initiate a systemcalibration; and compare the activation value with a third predeterminedvalue, the third predetermined value being greater than the secondpredetermined value and less than the first predetermined value, and ifthe activation value is greater than the third predetermined value, setan alarm.
 6. The storage drive of claim 1, further comprising anequalizer coupled between the sampler and the detector, the equalizercomprising an adaptive FIR filter having a plurality T of taps of whichn taps are coupled to the interface, wherein the potential statesrepresented by the exemplar vectors comprise potential states of the FIRtaps.
 7. The storage drive of claim 6, wherein the processor is furtheroperable to convert the values of the FIR taps from the time domain tothe frequency domain to substantially remove ambiguities associated withthe FIR taps.
 8. The storage drive of claim 6, wherein the processor isfurther operable to select the n taps to couple to the interface, wheren<T.
 9. A method for evaluating the state of an adaptive equalizer in adata storage drive read/write channel, comprising: generating aplurality J of n-tuple exemplar vectors representative of potentialstates of the equalizer; operating the read/write channel; generating ann-tuple trial vector from n FIR tap values representing an actual stateof the equalizer; of the J exemplar vectors, identifying an exemplarvector K which is closest to the trial vector, the distance from thetrial vector to the identified exemplar vector K being an activationvalue; whereby, if the activation value is less than a firstpredetermined value, the actual state of the equalizer is characterizedby the exemplar vector K.
 10. The method of claim 9, wherein generatingthe exemplar vectors comprises: initializing a plurality J of n-tupleunprocessed exemplar vectors with random values; globally conditioningthe J unprocessed exemplar vectors; separating the conditionedexemplars; and consolidating the separated exemplar vectors.
 11. Themethod of claim 10, wherein globally conditioning the J unprocessedexemplar vectors comprises: sequentially applying a plurality M of inputvectors to the J unprocessed exemplar vectors; updating the Junprocessed exemplar vectors by a factor of α₁; and repeating theapplying and updating steps over a predetermined number e₁ of epochs.12. The method of claim 10, wherein separating the conditioned vectorscomprises: sequentially applying the plurality M of input vectors to theJ conditioned exemplar vectors; of the J conditioned exemplar vectors,selecting the conditioned exemplar vector which is closest to thecurrently applied input vector; updating the selected conditionedexemplar vector and a predetermined number of adjoining conditionedexemplar vectors by a factor of α₂; and repeating the applying,selecting and updating steps over a predetermined number e₂ of epochs.13. The method of claim 10, wherein consolidating the separated vectorscomprises: sequentially applying the plurality M of input vectors to theJ separated exemplar vectors; of the J separated exemplar vectors,selecting the separated exemplar vector which is closest to thecurrently applied input vector; updating the selected conditionedexemplar vector by a factor of α₃; and repeating the applying, selectingand updating steps over a predetermined number e₃ of epochs.
 14. Themethod of claim 9, further comprising normalizing each unprocessedexemplar vector and the trial vector to a predetermined magnitude. 15.The method of claim 9, wherein identifying the exemplar vector K whichis closest to the trial vector comprises calculating the Euclideandistance between each exemplar vector and the trial vector.
 16. Themethod of claim 9, whereby, if the activation value is greater than thefirst predetermined value, the trial vector is invalid.
 17. The methodof claim 9, further comprising: if the activation value is less than asecond predetermined value, the second predetermined value being lessthan the first predetermined value, logging the activation value; if theactivation value is greater than the second predetermined value,initiating a read/write channel calibration; and if the activation valueis greater than a third predetermined value, the third predeterminedvalue being greater than the second predetermined value and less thanthe first predetermined value, setting an alarm.
 18. The method of claim9, further comprising converting the FIR tap values from the time domainto the frequency domain to substantially remove ambiguities associatedwith the FIR taps.
 19. The method of claim 9, wherein the equalizercomprises a plurality T of FIR tap values, the method further comprisingselecting the n taps to couple to the interface, where n<T.
 20. Acomputer program product of a computer readable medium usable with aprogrammable computer, the computer program product havingcomputer-readable code embodied therein for evaluating the state of anadaptive equalizer in a data storage drive read/write channel, thecomputer-readable code comprising instructions for: operating the datastorage drive; generating an n-tuple trial vector from n parametersrepresenting an actual state of the data storage drive; retrieving aplurality of n-tuple exemplar vectors from a memory, each exemplarvector representing a potential state of the data storage drive; and ofthe J exemplar vectors, identifying an exemplar vector K which isclosest to the trial vector, the distance from the trial vector to theidentified exemplar vector K being an activation value; whereby, if theactivation value is less than a first predetermined value, the actualstate of the data storage drive is characterized by the exemplar vectorK.
 21. The computer program product of claim 20, wherein theinstructions further comprise instruction for normalizing the trialvector to a predetermined magnitude.
 22. The computer program product ofclaim 20, wherein the instructions for determining which exemplar vectorK is closest to the trial vector comprise instructions for calculatingthe Euclidean distance between each exemplar vector and the trialvector.
 23. The computer program product of claim 20, whereby, if theactivation value is greater than the first predetermined value, thetrial vector is invalid.
 24. The computer program product of claim 20,wherein the instructions further comprise instructions for: logging theactivation value if the activation value is less than a secondpredetermined value, the second predetermined value being less than thefirst predetermined value; initiating a system calibration if theactivation value is greater than the second predetermined value; andsetting an alarm if the activation value is greater than a thirdpredetermined value, the third predetermined value being greater thanthe second predetermined value and less than the first predeterminedvalue.
 25. The computer program product of claim 20, wherein theinstructions for generating an n-tuple trial vector further compriseinstructions for obtaining the values of n taps from an adaptive FIRfilter in an equalizer in the data storage drive and wherein thepotential states represented by the exemplar vectors comprise potentialstates of the FIR taps.
 26. The computer program product of claim 25,wherein the equalizer comprises a plurality T of FIR tap values and theinstructions for generating an n-tuple trial vector further compriseinstructions for selecting the n taps, where n<T.
 27. The computerprogram product of claim 25, wherein the computer-readable code furthercomprise instructions for converting the FIR tap values from the timedomain to the frequency domain to substantially remove ambiguitiesassociated with the FIR taps.